Investigation of Metal Cation Effects on Corrosion Behavior of Aluminum Alloys

PurposeThe purpose of this paper is to investigate the effects of inorganic inhibitors on the corrosion rate of aluminum alloy using the electrochemical noise (EN) analysis and electrochemical impedance spectroscopy (EIS) techniques.Design/methodology/approachEN and EIS measurements were employed to study the corrosion behavior of aluminum alloy in Na2SO4(0.50 M)/NaCl(0.20 M) solution in presence of inorganic inhibitors. The time‐series noise patterns were transformed into the frequency domain using fast Fourier transformation, and then their power spectrum densities (PSDs) at specified frequencies were determined and compared with the EIS and polarization results.FindingsThe EN, EIS and polarization results were in agreement. The inhibitive effect of the anions decreased in the order: CrO42−>Cr2O72−>NO3−>WO42−>MoO42−>NO2−. The results showed that the slope of PSD of the current (i.e. the “roll off”) was less where inhibition efficiency was greater. The spectral noise impedance and the modulus of the impedance recorded using impedance spectroscopy showed good agreement.Originality/valueThis paper provides useful information relative to corrosion inhibition efficiency of the sodium and potassium salts using EN analysis technique.

Purpose – The purpose of this paper is to investigate the corrosion behaviors of 2A12 aluminum alloy in NaCl and EXCO solution, and establish the relationship between the corrosion depth and the time. Design/methodology/approach – Alternate immersion corrosion test chamber was used to perform the corrosion test. The corrosion mediums were 3.5 percent NaCl solution and EXCO solution (NaCl 234 g/L, KNO3 50 g/L, 68 percent HNO3 6.8 mL/L). The surface morphology was studied using the digital microscope. Findings – The average corrosion rate of aluminum alloy in NaCl solution decreased gradually at the initial stage and then went to a plateau value. The average corrosion rate of aluminum alloy in EXCO solution increased first, then showed a downward trend. The empirical function D=At B was verified. Originality/value – The results could provide a reference for the establishment of accelerated environmental spectrum in the laboratory and give instructions on the application of aluminum alloy in alternated dry and wet environment.

Effect of Al2O3 nanoparticles on the corrosion behavior of aluminum alloy in simulated vehicle coolant

The influence of metal cations on corrosion behavior of aluminum alloy (AA2024-T3) in model freshwater was examined by immersion experiments, surface analysis, and electrochemical measurements. After long-time immersion, the corrosion rate of AA2024-T3 decreased as the corrosion indicator Y increased, and the corrosion rate of the alloy was reduced by Zn2+. The specimen immersed in Zn2+ containing solution showed less corrosion products which were observed by scanning electron microscopy (SEM). The results of X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) showed that Zn2+ attaches to aluminum alloys and forms protective layers. Electrochemical impedance spectroscopy (EIS) results suggested that Zn2+ reduced the area of defects in the passive film.

In this study, the corrosion behaviour of several aluminium alloys in ethanol fuels was investigated by immersion and polarization tests. The corrosion properties of cast aluminium alloys (Al–17wt%Si–4wt%Cu–Mg, Al–8wt%Si–3wt%Cu, Al–7wt%Si–Mg and Al–17wt%Si–4wt%Cu–Mg with a chemically deposited nickel layer) in ethanol blended gasoline fuels were examined at various ethanol and water contents and various temperatures. Electrochemical and gravimetric measurements revealed a pronounced acceleration of the corrosion process above the boiling point. Additions of water restrain the corrosion. Increasing the ethanol content and the temperature leads to a higher corrosion sensitivity of the aluminium alloys. Furthermore, the nickel layer is very protective in all tested fuels. For aluminium alloys, a theory of the corrosion process in ethanol blended gasoline fuels is proposed.

Corrosion behavior of 7B04 aluminum alloy under the synergistic effect of Lacticaseibacillus paracasei and Acinetobacter lwoffi

Microbial corrosion behavior and mechanism of 5A06 aluminum alloy under low dose proton radiation

In microbiologically influenced corrosion (MIC) caused by sulfate-reducing bacteria (SRB), extracellular electron transfer (EET) between metals and microorganisms affects the metal corrosion process. In this work, the effect of the electron mediator riboflavin on the EET-MIC behavior of 2024 aluminum alloy (AA2024) was investigated by electrochemical methods, surface analysis techniques, focused ion beam, scanning electron microscopy, and x-ray photoelectron spectroscopy techniques. The results showed that the electron mediator was significantly able to accelerate SRB attack against AA2024. SRB utilized to consume H+ to accelerate its own metabolism and promoted the corrosion of AA2024, resulting in the formation of corrosion product AlOOH and Al(OH)3. The addition of electron mediator riboflavin increased the electron transfer efficiency and affected the reaction rate constant to accelerate the corrosion rate of aluminum alloy. The addition of 10 ppm riboflavin led to denser corrosion product biofilms on the surface of the aluminum alloy, which accelerated the formation of NaAlO2. Cl− diffused into the film layer through the pores of the surface of the aluminum alloy and was adsorbed into the film layer to induce pitting corrosion on the surface of the aluminum alloy. A large amount of SRB was attached, which resulted in an increasing pit depth on the surface of the aluminum alloy. Riboflavin accelerated the electron transfer process from the surface of the aluminum alloy across the cell wall to the cytoplasm, which led to serious corrosion of the aluminum alloy. The distribution of SRB in biofilm and the longitudinal distribution of bacteria in the process of pitting corrosion showed that the addition of electron mediators increased the depth of pits in aluminum alloys. Bacteria in the pitting area gathered at the bottom of the biofilm, and the pits were rich in Ca, P, and other elements.

The corrosion behavior of several high-strength aluminum alloys was characterized. The alloys were exposed to solutions of artificial seawater, some of which contained nitrate ion. Alloys were tested in the seawater solutions at room temperature and elevated temperature conditions. A unique synergism was discovered when nitrate anion was present in seawater; the synergism between nitrate anions and seawater greatly accelerated the intergranular corrosion of AA7075 alloys. This environment was relatively benign toward the alloys AA6061, PM7XXX, IN9052, and IN905XL. A mechanism to account for the observed synergism, which was recreated by mixing nitrate salts with artificial seawater, is proposed herein. The importance of grain boundary microstructure and chemical composition is discussed with respect to intermetallic reactivity and connectivity.

In this paper, the effect of corrosion behaviour of aluminium alloy 2014 were studied by potentiodynamic polarization in 1 mole of NaCl solution of aged sample. The experimental testing results concluded that, corrosion resistance of Aluminum alloy 2014 degraded with the increasing the temperature (150°C & 200°C) and time of ageing. Corroded surface of the aged specimens was tested under optical microscopes for microstructures for phase analysis. Optical micrographs of corroded surfaces showed general corrosion and pitting corrosion. The corrosion resistance of lower ageing temperature and lower ageing time is higher because of its fine distribution of precipitates in matrix phase.

Laser welding of 6061 aluminum alloy often results in coarse microstructures and inferior corrosion resistance due to rapid solidification. This study introduces ultrasonic vibration as an auxiliary technique to address these limitations. The paper systematically investigates the influence of laser weld ultrasonic assistance on the microstructure and corrosion behavior of a 6061-T6 aluminum alloy welded joint. The results demonstrate that ultrasonic assistance refined the grain structure and reduced the corrosion current density by 19.1% compared to conventional laser welding, achieving 73.6% of the base metal’s corrosion resistance. The enhancement is attributed to ultrasonic-induced acoustic streaming and cavitation, which promote equiaxed grain formation and impede corrosive penetration. The enhancement is attributed to ultrasonic-induced acoustic streaming and cavitation, which promote equiaxed grain formation and impede corrosive penetration. Under the ultrasonic effect, the number of dimples in the weld fracture increased and the depth was significant, which enhanced the tensile strength of the 6061 Aluminum alloy weld. This work provides a reliable and efficient strategy for producing high-performance aluminum alloy welded structures in industrial applications.

Effect of chemical cleaning on the corrosion behaviour of painted aluminium alloys

This experimental study focuses on the corrosion behavior of aluminum alloys in hydrogen sulfide (H2S) gas and liquid phases. The corrosion behaviors of 3A21, 6061, and 6063 aluminum alloys are investigated via scanning electron microscopy, energy dispersive spectroscopy, and thermogravimetry-differential scanning calorimetry. The results show that the corrosion rates of the three types of aluminum alloys increase with temperature, and the slope of the corrosion rate curve decreases gradually after reaching a certain temperature. At 75 °C, the corrosion rate reached 0.0675 mm/a, 0.0881 mm/a and 0.0613 mm/a in the gas phase, respectively. The corrosion products show white-yellow-gray irregular pits and a honeycomb-like morphology, and the main components are aluminum hydroxide, alumina, and aluminum sulfide. In particular, the 6061 aluminum alloy presents the most severe corrosion in H2S gas. Compared with the H2S gas phase, the corrosion rate in the liquid phase is higher. Additionally, the irregular pitting and honeycomb-like morphologies are more evident. Corrosion becomes more significant as temperature increases. Although the corrosion products in the two phases are composed of the same components, the content in the liquid phase is higher. The heat absorption and mass loss of the corrosion products present the same regularity. This indicates that the corrosion of the H2S liquid phase on the aluminum alloy is more significant than that of the H2S gas phase.

Corrosion behaviour of laser-cleaned AA7024 aluminium alloy

Effect of ageing temperature on microstructure, mechanical property and corrosion behavior of aluminum alloy 7085